Irradiance output of solid-state lighting devices may be influenced by operating temperature. Consequently, if the solid-state lighting device is at room temperature and a constant voltage is applied to the solid-state lighting device, the irradiance output from the solid-state lighting device may be greater than if the same constant voltage were applied to the same solid-state lighting device at the solid-state lighting device's nominal operating temperature.
Solid-state lighting devices have many uses in industrial applications. For example, ultraviolet (UV) solid-state lighting devices may be used to curing photo sensitive media such as coatings, including inks, adhesives, preservatives, etc. Curing time of these photo sensitive media may be responsive to solid-state lighting device irradiance output. Consequently, if the solid-state lighting devices operate at temperatures away from their nominal operating temperature, photo sensitive media may not cure sufficiently or electrical power consumption may increase due to changes in solid-state light device irradiance levels.
The inventor herein has recognized the above-mentioned disadvantages and has developed a system for operating one or more light emitting devices, comprising: at least one light emitting device; a negative temperature coefficient device in thermal communication with the at least one light emitting device; and an amplifier including a negative feedback loop, the negative temperature coefficient device included in the negative feedback loop.
By incorporating a negative temperature coefficient device into a negative feedback loop of an amplifier that controls current flow through one or more light emitting devices, it may be possible to more precisely control light emitting device irradiance over a wide range of operating temperatures. For example, when temperature of light emitting devices is lower than a nominal operating temperature of the light emitting devices, current flowing through the light emitting devices may be restricted or limited so that the light emitting devices output a substantially constant irradiance level corresponding to an irradiance level of when the light emitting devices are operated at the nominal operating temperature. In this way, the irradiance output of light emitting devices may be controlled to a substantially constant level so that curing of photo sensitive media may be more precisely controlled.
The present description may provide several advantages. In particular, the approach may improve lighting system light intensity control. Further, the approach may provide lower power consumption via providing efficient electrical current control. Further still, the approach may provide more consistent curing of photo sensitive media.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.